Universal coupler for excavator buckets

ABSTRACT

The coupler has a pair of spaced side frames ( 25   a ) in each of which a first hook like aperture ( 13 ) is provided for engagement with a first pivot pin provided on an excavator bucket and wherein a locking pin ( 23 ) is moveable from and into a locking position in which it prevents the latching hook ( 17   a ) from disengage from a second pivot pin ( 9   a ), ( 9   b ) or ( 9   c ) on the bucket there being a plurality of locking positions for the pin to accommodate different buckets. Preferably, a plurality of spaced apertures ( 27 ), ( 29 ), ( 31 ) are formed on each of the side frames ( 25   a ), those in one frame being transversely aligned with those in the other frames, and preferably also a plurality of spaced apertures ( 33, 35 ) and/or latching surfaces are formed on the latching hook or on an extension thereof, through or against which the locking pin ( 23 ) can be passed or can bear to prevent relative movement between the hook ( 17   a ) and side frames. Preferably, the piston end cylinder device ( 19   a ) for operating the latching hook has a much longer stroke than usual and the side frames ( 25   a ) of the coupler are longer than those of known couplers, there being a downwardly opening recess ( 15   a ) in the side frames which is much wider than usual to accommodate different pin spacings on the buckets of different manufacturers.

This invention relates to a universal coupler for bucket excavator.

Hydraulically operated mechanical excavators have a dipper arm on theend of which are two mounting points by means of which an excavatingbucket is pivotally attached to the end of the arm, and pivoted relativeto the arm, respectively. Until relatively recently, if the operatorwished to change the bucket, e.g. to a larger one, this had to be donemanually. This involved the operator leaving the cab of the excavator,removing two pivot pins by means of which the bucket is connected to thedipper arm, getting back into the cab to lift the dipper arm clear ofthe bucket, aligning the dipper arm with the new bucket (and aligningthe pivot apertures), dismounting from the cab again, and locating thepivot pins in the aligned apertures, and securing them in place (e.g.with circlips, locking pins or bolts or the like) and then getting backinto the cab to use the excavator. Sometimes, the operator would haveconsiderable difficulty in removing or re-inserting the pivot pins, dueto slight misalignment of the pivot apertures, and would have to use aheavy hammer for this purpose.

More recently, this time consuming exercise has been largely dispensedwith, with the introduction of quick couplers which are located betweenthe dipper arm and the bucket. The couplers can be of the mechanicaltype, but it is more normal now to provide a hydraulic type which can beoperated from the cab of the excavator. The couplers are thuspermanently fitted to the two pivot apertures of the dipper arm and thebucket pivoting link, respectively. These couplers incorporate agenerally horizontally and rearwardly extending hook-like aperture orjaw adapted to engage with one of the pivot pins on the bucket (both ofwhich are left fitted to the bucket), and a generally downwardlyextending recess adapted to locate over the other pivot pin on thebucket, with which downwardly extending recess a moveable latching hookis associated.

In the manual version of the coupler, this latching hook is biased by acoil spring to its latching position, and is moved away from itslatching position by a release handle or lever rod which is removablylocatable in an aperture in the nose of the latching hook.

In the hydraulic version, a double acting hydraulic piston and cylinderdevice moves the latching hook between its respective positions, andcheck valves are located within the piston and cylinder device toprevent inadvertent movement of the piston in the event of hydraulicfailure.

In both the manual and hydraulic versions, a safety device has to beprovided. This may be a pin which must be located by the excavatoroperator in specially provided apertures in the coupler, to lock thelatching hook in its latching position. The digger operator has to leavehis cab to secure in position the safety pin. However, in U.K. PatentNo. 2330570, there is a disclosure of a hydraulically operated lockingmeans which replaces the pin. This is very satisfactory, but is anexpensive option.

One of the disadvantages of these known couplers is that they have allbeen designed for use with one particular make of excavator, and thebuckets and other tools designed for use with the excavator(s) of thatmake, i.e. the excavator(s) of a particular manufacturer. This meansthat such couplers often cannot be used to pick up a bucket or the toolof another manufacturer. This can be a substantial disadvantage,especially on sites where there may be excavators from several differentmanufacturers all being operated by the same contractor(s).

It is an object of the present invention to provide a universal couplerfor an excavator which can be used by an excavator operator to pick upand use buckets and other tools made by different manufacturers, whichmay be different from the manufacturer of the excavator itself.

According to the present invention, we provide a coupler to enable anexcavator operator to couple an excavator bucket to a dipper arm of anexcavator while in his cab, the coupler including a pair of spaced sideframes and being mountable upon or having means by means of which it canbe coupled to the dipper arm of the excavator, a first hook-likeaperture in each side frame for engagement with a first pivot pinprovided on an excavator bucket, a power operated latching hook locatedbetween the side frames and supported for pivoting relative to theframes and operable by the operator from his cab for latching engagementwith a second pivot pin provided on the bucket once the first hook-likeaperture has been engaged with the first pivot pin, and a locking pinmoveable from and into a locking position in which it prevents thelatching hook from being disengaged from the second pivot pin on thebucket, and wherein there are a plurality of locking positions for thepin, to accommodate different buckets.

Preferably, a plurality of spaced apertures is formed in the sideframes, those in one frame being transversely aligned with those in theother side frame. Preferably, also, a plurality of spaced aperturesand/or latching surfaces is formed on the latching hook or an extensionthereof, through which said locking pin can be passed to restrictrelative movement between the hook and side frames.

Preferably, the latching hook is operated by means of a double actingpiston and cylinder device, one end of which is pivotally connectedabout a first pivot axis relative to the coupler side frames, and theother end of which is pivotally connected to the latching hook. Thispiston and cylinder device has a much longer stroke than that used inknown couplers. This means that the arc through which the latching hookcan be pivoted is greater than on known couplers.

Furthermore, the side frames of the coupler are preferably longer thanthose of known couplers.

Preferably, as well as the hook-like aperture formed in each side frame,there is a recess to receive the second pivot pin on the bucket, thisrecess opening downwardly and at 90° to the hook-like aperture, andbeing substantially wider than the width of the equivalent recess onknown couplers, to compensate for different pin spacings on the bucketsor other tools of different manufacturers.

Although the piston and cylinder device for the latching hook isprovided with a check valve and the locking means is provided, it isimportant that maximum provision is made to ensure that a bucket cannotaccidentally become disconnected from the coupler, and preferablytherefore, the latching hook is designed so that it will not rotate to arelease position when under load, or when there is a hydraulic failurein the piston and cylinder device controlling the hook, and when thelocking pin is not present.

In the present invention, we preferably provide a hook which has aninternal profile such that under the above conditions, and when the hookis carrying the weight of the bucket, and there would otherwise be atendency for the hook to rotate to a release position, the pin willcause the hook to swing about the pivot towards a latching position.

For this purpose, the free end of the hook has an upturned, extendednose, and the inner face of the book is of shallow V-shaped crosssection, thus forming a cradle for the pin.

A preferred embodiment of coupler according to the present invention isnow described by way of example with reference to the accompanyingdrawings, in which:

FIG. 1 is a side elevation of a prior art coupler showing how thecoupler is used to connect an excavator bucket to a dipper arm of anexcavator;

FIG. 2 is a partly schematic side elevation to a larger scale of thecoupler of FIG. 1;

FIG. 3 is a side elevation of the coupler of the present invention; and

FIGS. 4-6 are partly schematic side elevations with parts broken away,showing details of the coupler of FIG. 3 being coupled to threedifferent buckets (only the pin of the bucket being illustrated).

Referring to FIG. 1 of the drawings, an excavator bucket is shown at 1,and the distal end of an excavator dipper arm is shown at 3. Inaccordance with standard practice, the dipper arm 3 supports a bucketpiston and cylinder device 4 for controlling the bucket 1 via twoparallel pivot links 6. The bucket 1 is normally connected directly tothe dipper arm 3 by means of a first pivot pin 7 carried by the bucketand engaging directly within a mounting point or pivot aperture in anend region of the dipper arm 3 and by a second pivot pin 9 engagingdirectly within a mounting point or pivot aperture 5′ in an end regionof one of the links 6 (this arrangement is not shown).

More recently, however, a coupler 11 has been used to enable thesemi-automatic connection of the bucket 1 to the dipper arm 3 and asillustrated, the coupler has two mounting points thereon by means ofwhich it is connected to the mounting points 5 and 5′ on the dipper arm3 and on the link 6 respectively, by suitable connecting pins 12. Thecoupler 11 is provided in a lower region thereof with a first generallyhorizontally and rearwardly extending hook-like aperture or jaw 13 and asecond generally downwardly opening recess or jaw 15. By rearwardlyextending, we mean opening outwardly, in use, from the coupler towardsthe operator of an excavator on which the dipper arm and coupler arefitted and by downwardly opening we mean, in use, extending or openingoutwards generally downwards towards the ground. In order to connect thebucket 1 to the dipper arm, the excavator operator manoeuvres the dipperarm to the position shown in FIG. 1 and then moves the dipper armdownwardly and rearwardly so as to engage the first aperture or jaw 13with the first pivot pin 7, which is virtually permanently fitted to thebucket 1; he then operates the bucket-controlling piston and cylinderdevice 4 so as to swing the pivot links 6 downwardly, so as to move thesecond recess or jaw 15 into engagement with the second pivot pin 9,which is also virtually permanently secured to the bucket 1. The coupleris then latched in position with a latching hook (not shown in FIG. 1)so that the jaw 15 is clamped around the pin 9 and the bucket can beused for digging.

In FIG. 2, a latching hook 17 forming part of the prior art coupler ofFIG. 1 is shown, the hook 17 being pivotally supported on the body ofthe coupler about a pivot 18 and biased to a latching position (in whichit maintains the pivot pin 9 in the recess 15) by means of a piston andcylinder device 19, which is of course also used to move the hook 17 toa release position. The piston of the device 19 is pivotally connectedto the hook at 20 and the cylinder is pivotally connected to the body ofthe coupler at 22. A suitable check valve (not shown) is provided withinthe piston and cylinder device 19 in case there should be a failure inthe hydraulic supply to the piston and cylinder device 19. However, incase this check valve should fail, a safety pin 23 is always provided.This safety pin 23 bridges between two side frame 25 of the coupler 11and abuts against a rear face of the latching hook 17 so as to hold thelatching hook 17 in a latching position and prevent the bucket pivot 9from being released from the recess 15. The disadvantage with thisarrangement is that there is very little tolerance in the spacingbetween the bucket pins 7 and 9. If the spacing is too great or toosmall, the coupler cannot be used.

Referring now to FIG. 3, the coupler of the invention differs from thatof FIG. 2 in its overall shape and size, and general constructions ofthe side frames identified at 25 a. As in the prior art construction,two mounting points are provided for connecting the coupler to thedipper arm using the pins 12, and the frames 25 a are each provided witha first rearwardly extending hook like aperture or jaw 13 for a firstbucket pin (not shown). The frames 25 a are longer than the frames 25,and a much wider downwardly opening recess or jaw 15 a is providedinstead of the recesses 15, in each frame 25 a. Furthermore, threeclosely adjacent, but spaced circular holes 27, 29 and 31 are formed ineach of the frames 25 a, so as to provide three sets of holes, the holesof each set being directly opposite one another in the respective frames25 a, thus providing three different locations for a locking pin 23 (seeFIGS. 4-6).

As can be seen from FIGS. 4-6, the only differences between the figuresare in the locations of the bucket pins 9 a, 9 b and 9 c in the recess,and in the locations of the latching hook 17 a and of parts associatedwith the hook 17 a.

Referring first to FIG. 4, the location of the central of the firstpivot pin 7 of a bucket (not shown) is identified at X, when the pin issnugly received in the aperture 13. The recess 15 a is substantiallywider than the diameter of the second bucket pin 9 a, which is shownlocated in a central region of the recess 15 a. The distance between thecentres of the pins 7, 9 a is D¹.

As can be seen from FIG. 5, a different bucket having bucket pins 7 and9 b, which have their centres spaced apart by a distance D² (whereD¹>D²) has been picked up by the coupler.

As can be seen in FIG. 6, another different bucket having bucket pins 7and 9 c, has this time been picked up by the coupler. On this bucket,the spacing between the centres of the bucket pins 7 and 9 c is D³, whenD³>D¹>D².

As well as requiring a particularly wide recess 15 a to accommodatebuckets having pins with different spacings between their centres, it isnecessary that the latching hook 17 a is able to swing through differentarcs to latch the respective pins 9 a, 9 b or 9 c in the recess 15 a.This is achieved by providing a piston and cylinder device 19 a with apiston throw which is much longer than that of the piston and cylinderdevice 19 of the prior art coupler. This ensures that with all three (orfor that matter all appropriate) bucket pin spacings, the latching hook17 a can be swung by an appropriate amount from a bucket releaseposition (not shown) to a pin locking position.

As described with reference to FIG. 3, three sets of holes 27, 29, 31for the locking pin 23 are provided in the side frames of the coupler sothat, regardless of the position of the latching hook 17 a, it can stillbe latched in its pin locking position.

As can be seen from each of FIGS. 4-6, the hook 17 a has a locking plate36 projecting from a rear portion thereof with a first locking aperture33 therein, a second locking aperture 35 therein, and a locking surface37 thereon. Each of the apertures 33 and 35 is of elongate arcuateconstruction, so as to provide a degree of universality. As can be seenfrom FIG. 4, for a bucket pin spacing of D¹, the locking pin 23 islocated in the aperture 35 and passes through the holes 31 in thecoupler side frames. However, in FIG. 5, where the coupler is being usedwith a bucket having pin spacings of D², the locking pin 23 is locatedin the aperture 33, and passes through the holes 27 in the side frames25 a. However, in FIG. 6, where the coupler has picked up a bucket witha pin central spacing of D³, the locking pin 23 engages against thelocking surface 37, and passes through the holes 29 in the side frames25 a. Hence, with all three buckets having different pin spacings, it ispossible to find a set of aligned holes in the coupler side frames whichare aligned with one of the apertures 33, 35 or the surface 37. Itshould be noted, however, that for each different pin spacing, therewill only be one set of aligned holes in the coupler side frames whichare aligned with one of the apertures 33, 35 or the surface 37. Hence,it is not possible to insert the locking pin 23 in a “wrong” set ofholes 27, 29 or 31, and not latch the hook 17 in a pin locking position,because two of the three sets of holes 27, 29, 31 will be blocked off atany one time by the hook 17 a or the plate 36.

In practice, there are many different manufacturers of excavators all ofwhom produce buckets with different pin spacings, and the coupler of thepresent invention, due to its universality, can be used to pick up themajority of these buckets and have its locking hook 17 a latched in itslocking position using a locking pin 23.

In spite of the safety feature described above (provision of the pin23), there is still a slight risk, e.g. in the event of operator misuse,such as not fitting the pin 23, that the latching hook 17 a may swing toits unlatching position, thus allowing the bucket to be dropped from thedipper arm if there is a hydraulic failure, and if the check valve inthe piston and cylinder device 19 fails. Accordingly, we prefer toprovide a latching hook 17 a which, under normal conditions, cannotswing to an unlatched position, due to the weight of the bucket pivot 9thereon.

Normally, with most prior art latching hooks, the weight of the bucketon the hook, which is transferred to the hook through the bucket pin 9,will cause the hook to swing clockwise as shown in FIGS. 4-6, due to thereaction force acting on the inner concave face of the hook, causing thehook to move to an open position. However, as is shown in FIGS. 4-6, thepreferred hook of the invention has an internal profile in the form of ashallow V, as shown at 39 in FIG. 4 and an extended nose portion 41. Theconfiguration of the internal profile is such that, when the bucket pinis bearing down upon the shallow V-shaped concave portion 39 of thehook, there will be a reaction force generated such that the momentacting on the hook 17 a about its support pivot is anticlockwise, thustending to move the hook to its locking position.

In the prior art coupler illustrated in FIGS. 1 and 2, the length of thecylinder 19 is about 265 mm and the length of the stroke of the cylinderis about 100 mm. This coupler could accommodate buckets (or other tools)with a pin spacing of 446 mm (between centres).

In a preferred example of coupler according to the present invention thecylinder 19 a is about 310 mm long, and the length of its stroke isabout 140 mm. Furthermore, the side frames 25 a are about 20% longerthan the side frames 25 of the prior art coupler, which means that thecoupler of this invention can accommodate bucket pin spacings betweenabout 435 mm and 520 mm. There is an increase in the length of therecess 15 a of about 90 mm relative to the length of the prior artrecess 15. The base of the recess 15 a is slightly “humped” at a centralregion to ensure that a bucket pin located in the recess always sits ina same region of the hook 17 a regardless of the bucket pin spacing.This ensures that both the stresses within the hook and the bucketclamping force remains constant.

It will of course be understood that the present invention has beendescribed above purely by way of example, and modifications of detailcan be made within the scope of the invention.

1. A coupler to enable an excavator operator to couple an excavatorbucket to a dipper arm of an excavator while in his cab, the couplerincluding a pair of spaced side frames and being mountable upon orhaving means by means of which it can be coupled to the dipper arm ofthe excavator, a first hook-like aperture in each side frame forengagement with a first pivot pin provided on the excavator bucket, apower operated latching hook located between the side frames andsupported for pivoting relative to the frames and operable by theoperator from his cab for latching engagement with a second pivot pinprovided on the bucket once the first hook-like aperture has beenengaged with the first pivot pin, a plurality of spaced apart aperturesin each side frame and a locking pin moveable from and into a pluralityof locking positions in the spaced apart apertures in which it preventsthe latching hook from being disengaged from the second pivot pin on thebucket.
 2. A coupler according to claim 1, wherein the plurality ofspaced apertures formed in one side frame are transversely aligned withthose in the other side frame.
 3. A coupler according to claim 1,wherein, a plurality of spaced apertures and/or latching surfaces isformed on the latching hook or on an extension thereof, through oragainst which said locking pin can bear to restrict relative movementbetween the hook and side frames.
 4. A coupler according to claim 1,wherein the latching hook is operated by means of a double acting pistonand cylinder device, one end of which is pivotally connected about afirst pivot axis relative to the coupler side frames, and the other endof which is pivotally connected to the latching hook.
 5. A coupleraccording to claim 1, wherein there is a recess to receive the secondpivot pin on the bucket, this recess opening downwardly and at 90° tothe hook-like aperture, and being sufficiently wide to compensate fordifferent pin spacings.
 6. A coupler according to claim 1, wherein thelatching hook is designed so that it will not rotate to a releaseposition when under load, or when there is a hydraulic failure in thepiston and cylinder device controlling the hook, and when the lockingpin is not present.
 7. A coupler according to claim 6, wherein thelatching hook has an internal profile such that, when the hook iscarrying the weight of the bucket, the bucket will cause the hook toswing towards a latching position.
 8. A coupler according to claim 6,wherein the free end of the hook has an upturned, extended nose, and theinner face of the hook is of shallow V-shaped cross section, thusforming a cradle for the pin of the bucket.
 9. A coupler according toclaim 2, wherein, a plurality of spaced apertures and/or latchingsurfaces is formed on the latching hook or on an extension thereof,through or against which said locking pin can bear to restrict relativemovement between the hook and side frames.
 10. A coupler according toclaim 2, wherein the latching hook is operated by means of a doubleacting piston and cylinder device, one end of which is pivotallyconnected about a first pivot axis relative to the coupler side frames,and the other end of which is pivotally connected to the latching hook.11. A coupler according to claim 3, wherein the latching hook isoperated by means of a double acting piston and cylinder device, one endof which is pivotally connected about a first pivot axis relative to thecoupler side frames, and the other end of which is pivotally connectedto the latching hook.
 12. A coupler according to claim 10, wherein thelatching hook is operated by means of a double acting piston andcylinder device, one end of which is pivotally connected about a firstpivot axis relative to the coupler side frames, and the other end ofwhich is pivotally connected to the latching hook.
 13. A coupleraccording to claim 2, wherein there is a recess to receive the secondpivot pin on the bucket, this recess opening downwardly and at 90° tothe hook-like aperture, and being sufficiently wide to compensate fordifferent pin spacings.
 14. A coupler according to claim 3, whereinthere is a recess to receive the second pivot pin on the bucket, thisrecess opening downwardly and at 90° to the hook-like aperture, andbeing sufficiently wide to compensate for different pin spacings on thebuckets.
 15. A coupler according to claim 4, wherein there is a recessto receive the second pivot pin on the bucket, this recess openingdownwardly and at 90° to the hook-like aperture, and being sufficientlywide to compensate for different pin spacings on the buckets.
 16. Acoupler according to claim 2, wherein the latching hook is designed sothat it will not rotate to a release position when under load, or whenthere is a hydraulic failure in the piston and cylinder devicecontrolling the hook, and when the locking pin is not present.
 17. Acoupler according to claim 3, wherein the latching hook is designed sothat it will not rotate to a release position when under load, or whenthere is a hydraulic failure in the piston and cylinder devicecontrolling the hook, and when the locking pin is not present.
 18. Acoupler according to claim 4, wherein the latching hook is designed sothat it will not rotate to a release position when under load, or whenthere is a hydraulic failure in the piston and cylinder devicecontrolling the hook, and when the locking pin is not present.
 19. Acoupler according to claim 5, wherein the latching hook is designed sothat it will not rotate to a release position when under load, or whenthere is a hydraulic failure in the piston and cylinder devicecontrolling the hook, and when the locking pin is not present.
 20. Acoupler according to claim 7, wherein the free end of the hook has anupturned, extended nose, and the inner face of the hook is of shallowV-shaped cross section, thus forming a cradle for the pin of the bucket.21. A coupler to enable an excavator operator to couple an excavatorbucket to a dipper arm of an excavator while in his cab, the couplercomprising: a pair of spaced side frames and being mountable upon orhaving means by means of which it can be coupled to the dipper arm ofthe excavator, a first hook-like aperture in each side frame forengagement with a first pivot pin provided on an excavator bucket, alatching hook located between the side frames and supported for pivotingrelative to the frames for latching engagement with a second pivot pinprovided on the bucket once the first hook-like aperture has beenengaged with the first pivot pin, and a locking pin moveable from andinto a locking position in which it prevents the latching hook frombeing disengaged from the second pivot pin of the bucket, wherein thecoupler comprises a plurality of locking positions for the pin foraccommodating buckets having different pivot pin spacings, the lockingpositions being defined by a plurality of spaced apertures formed in thespaced side frames, those in one frame being transversely aligned withthose in the other frame, wherein the locking pin, when inserted betweena first pair of the spaced apertures, will be able to restrict relativemovement between the hook and the side frames for a bucket having afirst pivot pin spacing and wherein the locking pin, when insertedbetween a second pair of the spaced apertures, will be able to engage alocking surface on an outer surface of the book, or an extensionthereof, to restrict relative movement between the hook and the sideframes for a second, different, bucket having a second, different, pinspacing; and wherein the latching hook is power operated and operable bythe operator from his cab.
 22. A coupler according to claim 21, whereina plurality of spaced apertures and the locking surface are formed in oron the hook, or an extension thereof, through or against which saidlocking pin can be passed or bear to restrict the relative movementbetween the hook and the side frames.
 23. A coupler according to claim21 wherein a plurality of spaced apertures and latching surfaces isformed on an extension of the hook, through or against which saidlocking pin can be passed or bear to restrict the relative movementbetween the hook and side frames.
 24. A coupler according to claim 21wherein the latching hook is operated by means of a double acting pistonand cylinder device, one end of which is pivotally connected about afirst pivot axis relative to the coupler side frames, and the other endof which is pivotally connected to the latching hook.
 25. A coupleraccording to claim 21 wherein there is a recess to receive the secondpivot pin on the bucket, this recess opening downwardly and at 90° tothe hook-like aperture, and being sufficiently wide to compensate forthe different pin spacings on the buckets or other tools of differentmanufactures.
 26. A coupler according to claim 21 wherein the latchinghook is designed so that it will not rotate to a release position whenunder load, or when there is a hydraulic failure in the piston andcylinder device controlling the hook and when the locking pin is notpresent.
 27. A coupler according to claim 26 wherein the latching hookhas an internal profile such that, when the hook is carrying the weightof the bucket, the bucket will cause the hook to swing towards alatching position.
 28. A coupler according to claim 26 wherein the freeend of the hook has an upturned, extended nose, and the inner face ofthe hook is of shallow V-shaped cross section, thus forming a cradle forthe pin of the bucket.